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Transcript of Agriculture
fertilizer Outputs: food Traditional intensive agriculture uses sun energy and irrigation. Irrigation systems replace rain water. Human and animal labor are utilized. Because animals are used regularly, their dung (poop) is used as fertilizer. In traditional intensive systems, farmers still practice and rely on polyculture, but they will sometimes specialize in one food so that they have enough leftover to sell and make some profit. They produce enough food for their own family and enough to sell as well. There is very little waste in this system because animal and food waste is reused as fertilizer. Inputs: lots of water, fossil fuels, chemical fertilizers, chemical pesticides. Outputs: Food for export, air pollution, water pollution, food waste, packaging waste. Since the 1950’s, industrial agriculture became commonplace in the U.S., Europe and other industrialized (developed) nations.
This system relies on high inputs and produces significant amounts of food. It also produces significant amounts of waste. An important characteristic of modern agriculture is monoculture - growing one type of food on one farm. This allows farmers to specialize and economize. Food can be grown more efficiently and cheaply. This modernization of food production, which began in the 1950’s, is called the Green Revolution. The green revolution was led, in part, by one man – Norman Bourlag. He was a humanitarian, plant biologist and agricultural scientist. He was motivated to feed the world and eliminate hunger. He was particularly concerned with people in developing nations and he won a Nobel Peace prize for his leadership in this field. He spear-headed efforts to develop dwarf varieties of crops. These are crops that can be grown and harvested quickly with the right amounts of water and fertilizer. They are utilized heavily in the tropics where 2 or 3 crops can be harvested in 1 year. But, these varieties reduce diversity and require large inputs of water and fertilizer. The Green Revolution has been successful. The graph below illustrates the increase in grain production between 1960 and 2010. But...... These gains have leveled off in terms of number of people that have been fed. Since about 1980, grain production per person has not increased. And, the practices used to produce food might not be sustainable. Modern agricultural practices contribute to soil erosion and loss of soil fertility. This map illustrates geographic patterns in the level of concern of the health of soil resources. Agriculture contributes to loss of biodiversity through habitat loss . Land is converted from natural habitats to farm fields. Wetlands are drained. Rainforests are converted to grow crops and cattle.
Monoculture reduces the genetic diversity of the food that we grow. Reduction in genetic diversity means that our crops are less resistant to drought, flood, pests or other environmental variations. Soil Texture Soil Fertility Soil: The uppermost layer of the Earth's crust is soil. It is a mixture of organic matter and mineral particles. The ability of soil to support plant growth is determined by the characteristics, or properties, of the soil. Agricultural activities impact these properties. And, can degrade the resource. Let's look more closely at soil. Soil texture is determined by the relative amounts of sand, silt and clay. Plant growth is dependent on soil texture. i.e. most plants require balanced soil with significant amounts of organic matter. Other plants grow in specific kinds of soil. For example, blueberries like sandy soil. Agriculture practices, like tilling or plowing, can cause soil erosion - the movement of soil components from one area to another. Exposed soil and rain contribute to soil erosion. Soil fertility is the variety of soil characteristics that support plant growth. Plants need macronutrients like nitrogen, phosphorous, and potassium as well as other nutrients to flourish. Different plants need different amounts of each. Monoculture reduces soil fertility and requires the addition of nutrients as fertilizers. Soil Fertility Soil fertility is the variety of soil characteristics that support plant growth. Soil fertility is impacted by pH - a chemical property of soil. Certain plants will grow in certain pH levels. Humans impact pH of soil through acid rain. Modern agricultural practices contribute to water problems in two ways. Overconsumption of water contributes to changes in the hydrologic cycle and water loss. And, runoff of fertilizer and pesticides contribute to water pollution. The water running off this farm field carries with it soil particles, fertilizers and pesticides. Each contributes to water pollution. Air pollution and energy use is a by-product of farm machinery emissions, food processing and food transport. Human health is impacted by chemical residues in water, food and air. Increases in meat production is a characteristic of agriculture in industrialized nations. Meat production has quadrupled between 1960 and 2005 and per capita meat production has doubled. This is largely due to increased amounts of meat consumption in affluent nations. Remember what we learned about energy transfer efficiency in food webs? In what level of the food web are cattle? Humans? This may be an explanation for the leveling off of the food produced per person that we discussed previously. Genetic technology has brought with it genetically modified organisms (GMO's). This is when geneticists take genes from one organism and insert them into another.
There is a raging debate about the pros and cons of GMO's. Is this a good thing? Genetically modified rice, golden rice, provides vital nutrition to millions of undernourished people in Southeast Asia. This video discusses the promise of golden rice, but also some of the criticisms and problems with this genetically enhanced food. Crops can also be engineered to resist herbicides like Round-up. The benefit is that farmers can use the herbicide after seedlings, like a soy crop, have emerged from the ground. This can reduce the amount of herbicide that a farmer has to use. But, what happens when these genes show up in unexpected places? Watch this video and think about that. Finally, there is the issue of pesticides. There are benefits. Pests have always been a problem in agriculture. By pests we mean weeds, insects, viruses, bacteria etc. Up to 30% of a farmer's crop can be lost to pests. Insecticides, herbicides, fungicides reduce crop loss to pests. There are cons Pesticides have been implicated in human health problems. They get into our water supply and cause both surface and groundwater pollution. Many pesticides, like DDT, have been known to harm wildlife like raptors. And, pesticide resistance can develop. What is pesticide resistance? Watch this video for an explanation. Over time, more and more species of pests have become resistant to pesticides. I am not sure I fully agree with this narrator's optimism. But, you get the idea. Modern agriculture feeds a lot of people. But, it has a large food footprint*. How do we reduce our food footprint? Sustainable Agricultural practices provide some solutions. Tilling methods Conclusion Sustainable agriculture: meeting the world’s food requirements in a way that is profitable, healthy for consumers and that can adapt to changing environmental conditions. For agricultural practices to be adaptable, they must conserve top
soil, retain organic matter, avoid contaminants, avoid pollution and maintain biological diversity. Contour plowing, terracing and shelterbelts reduce erosion. Cover crops Cover crops, called green manure, can maintain fertility and reduce erosion. Farmers establish vegetation, like clover, between growing seasons. This vegetation restores nitrogen levels, reduces winter erosion and when plowed under provides nutrients and organic matter to the soil. By removing the original crop and adding a new over-winter crop, pests are reduced and less pesticides will need to be used during the following growing season. Crop Rotation Different plants utilize different nutrients. Rotating crops allow some nutrients to build up in the soil while others are getting utilized. MSU’s organic farm uses a 7 year crop rotation.
Beans and corn are a common crop rotation here in Michigan. Through a symbiotic relationship with bacteria, beans restore the nitrogen used by the corn.
Crop rotation maintains fertility and reduces the need for pesticides. As a result, this practice also reduces water pollution. Biological pest controls Utilizing native insects, fungus or bacteria to control crop pests is a biological way of controlling pests. A classic example is the use of lady bugs in New England to eat aphids which attack alfalfa, wheat and corn. Some agriculturalists will use non-natives for this…What do you think about that? * Food footprint: the amount of water, fossil fuels, resources used and waste created to produce food. Integrated pest management is when a farmer uses both traditional pesticides and biological controls to keep pest numbers down. By combining these two forms of pest control, a farmer can use less pesticide, save money and still yield more crops. Integrated Pest Management Sustainable agriculture also uses a wider variety of seeds. More variety is better against pests and unexpected environmental change. Sustainable agriculture keeps all of the varieties, even those that are perceived as weak so that there is more genetic diversity later on, if needed. Preserve Diversity Drip irrigation with soil moisture sensors can add just the right amount of water to a field and can save a lot of water. This also means that there is less water to run-off and therefore, less pollution. Drip Irrigation Choosing foods that are in season and grown locally, that are fresh and unprocessed, and that were grown with sustainable principles reduce the amount of energy used to bring food to your table. Personal Choices These starving children are collecting ants to eat. It is an uncomfortable picture to view and it is a stark reminder that different countries face starkly different realities of food security and insecurity. Food security is when all or most of the people have access to enough nutritious food. Food insecurity is when people live with chronic hunger (under-nutrition) and poor nutrition (malnutrition).
Developed and developing nations have vastly different realities of food security. Many developed nations suffer from over-nutrition while developing nations struggle with food insecurity.
Poverty and politics are the two principal reasons for food insecurity. Organic matter in the soil helps maintain nutrients. Over the course of history, humans have gotten better and better at producing food. Modern agricultural practices produce enough food to feed the world. It is poverty and politics that prevent food from being distributed to everybody.
And unfortunately, these practices have several negative side-effects. Many agriculturalists worry that these practices are unsustainable and will eventually lead to less productive food production.